sql: use crdb_internal for pg_proc.pronamespace when needed

Release note (bug fix): The pronamespace column of the pg_proc table
now correctly reports the crdb_internal schema for built-in functions
that have the "crdb_internal" prefix.

pkg/sql/logictest/testdata/logic_test/pg_catalog

@@ -2242,20 +2242,21 @@ oid         typname  typnamespace  typowner    typlen  typbyval  typtype
 
 ## pg_catalog.pg_proc
 
-query TOOOTTO colnames
-SELECT proname, pronamespace, proowner, prolang, procost, prorows, provariadic
-FROM pg_catalog.pg_proc
+query TOTOOTTO colnames
+SELECT proname, pronamespace, nspname, proowner, prolang, procost, prorows, provariadic
+FROM pg_catalog.pg_proc p
+JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace
 WHERE proname='substring'
 ----
-proname    pronamespace  proowner  prolang  procost  prorows  provariadic
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
-substring  4294967129    NULL      0        NULL     NULL     0
+proname    pronamespace  nspname     proowner  prolang  procost  prorows  provariadic
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
+substring  4294967129    pg_catalog  NULL      0        NULL     NULL     0
 
 query TTBBBB colnames
 SELECT proname, protransform, proisagg, proiswindow, prosecdef, proleakproof
@@ -2317,6 +2318,18 @@ substring  NULL         substring  NULL    NULL       NULL
 substring  NULL         substring  NULL    NULL       NULL
 substring  NULL         substring  NULL    NULL       NULL
 
+query TTOTOT colnames
+SELECT proname, prosrc, pronamespace, nspname, prorettype, proargtypes
+FROM pg_catalog.pg_proc p
+JOIN pg_catalog.pg_namespace n ON p.pronamespace = n.oid
+WHERE proname='pb_to_json'
+ORDER BY p.oid
+----
+proname     prosrc      pronamespace  nspname        prorettype  proargtypes
+pb_to_json  pb_to_json  4294967295    crdb_internal  3802        25 17
+pb_to_json  pb_to_json  4294967295    crdb_internal  3802        25 17 16
+pb_to_json  pb_to_json  4294967295    crdb_internal  3802        25 17 16 16
+
 query TOIOTTB colnames
 SELECT proname, provariadic, pronargs, prorettype, proargtypes, proargmodes, proisstrict
 FROM pg_catalog.pg_proc

pkg/sql/pg_catalog.go

@@ -2328,10 +2328,16 @@ https://www.postgresql.org/docs/9.6/view-pg-prepared-statements.html`,
 	},
 }
 
-func addPgProcBuiltinRow(nspOid *tree.DOid, name string, addRow func(...tree.Datum) error) error {
+func addPgProcBuiltinRow(name string, addRow func(...tree.Datum) error) error {
 	props, overloads := builtinsregistry.GetBuiltinProperties(name)
 	isAggregate := props.Class == tree.AggregateClass
 	isWindow := props.Class == tree.WindowClass
+	nspOid := tree.NewDOid(catconstants.PgCatalogID)
+	if strings.HasPrefix(name, "crdb_internal.") {
+		nspOid = tree.NewDOid(catconstants.CrdbInternalID)
+		name = name[len("crdb_internal."):]
+	}
+
 	for _, builtin := range overloads {
 		dName := tree.NewDName(name)
 		dSrc := tree.NewDString(name)
@@ -2524,7 +2530,6 @@ https://www.postgresql.org/docs/9.5/catalog-pg-proc.html`,
 
 		err := forEachDatabaseDesc(ctx, p, dbContext, false, /* requiresPrivileges */
 			func(db catalog.DatabaseDescriptor) error {
-				nspOid := tree.NewDOid(catconstants.PgCatalogID)
 				for _, name := range builtins.AllBuiltinNames() {
 					// parser.Builtins contains duplicate uppercase and lowercase keys.
 					// Only return the lowercase ones for compatibility with postgres.
@@ -2536,7 +2541,7 @@ https://www.postgresql.org/docs/9.5/catalog-pg-proc.html`,
 					if unicode.IsUpper(first) {
 						continue
 					}
-					err := addPgProcBuiltinRow(nspOid, name, addRow)
+					err := addPgProcBuiltinRow(name, addRow)
 					if err != nil {
 						return err
 					}
@@ -2598,7 +2603,7 @@ https://www.postgresql.org/docs/9.5/catalog-pg-proc.html`,
 					return true, nil
 
 				} else {
-					err := addPgProcBuiltinRow(tree.NewDOid(catconstants.PgCatalogID), name, addRow)
+					err := addPgProcBuiltinRow(name, addRow)
 					if err != nil {
 						return false, err
 					}